As intelligent terminals are extensively applied, people have increasing requirements for data network traffic. To meet the requirements of people for data network traffic, performance of a network system needs to be enhanced continuously. Therefore, a wireless local area network is greatly evolved in this aspect, from the initial 802.11a/b to the 802.11g and 802.11n, and then to the 802.11ac. With continuous evolution of the standards, a throughput that can be provided by the system keeps increasing, and therefore meets various requirements of people for Internet access.
In an 802.11ac system, a very high throughput-long training field (VHT-LTF) included in an 802.11ac presentation protocol data unit (PPDU) structure is obtained through generation in time domain Code Division Multiplexing (CDM) mode. The VHT-LTF may be used to implement channel estimation for distinguishing multiple streams in a single user multiple-input multiple-output (SU-MIMO) scenario, or may be used to implement channel estimation for distinguishing multiple users in a multi-user multiple-input multiple-output (MU-MIMO) scenario.
The 802.11ac standard in the prior art is designed or acquired for an indoor environment. Compared with the indoor environment, an outdoor environment has a long multipath effect, and therefore to avoid interference between Orthogonal Frequency Division Multiplexing (OFDM) symbols, a cyclic prefix (CP) length needs to be increased. If a VHT-LTF is still generated in time domain CDM mode, multiple CPs required by multiple VHT-LTF symbols included in the VHT-LTF cause an increase in signaling overheads and a delay in reception of a data field.